In the manufacture of single face corrugated paperboard, a paper medium web is corrugated between two fluted corrugating rolls. Then the corrugated medium is retained on one of the corrugating rolls as it is moved past a rotating adhesive applicator roller. The applicator roller is positioned close to the fluted corrugating roll so that an adhesive bonding agent on the surface of the roller may be readily transferred to the crests of the fluted medium. The medium is then bonded to a web of liner board in the nip between one of the corrugating rolls and a juxtaposed pressure roll.
The corrugating and pressure rolls are heated generally with steam to a temperaturee of approximately 350.degree. to facilitate corrugating the medium and to effect bonding by the adhesive bonding agent. The adhesive bonding agent is generally a partially cooked solution of starch which gels to form an adhesive when exposed to heat.
From time to time, it is necessary to change the corrugating medium or to temporarily stop the single facer. If the adhesive applicator roller were allowed to remain in close proximity to the corrugating roll with no medium between them, the adhesive on the surface of the applicator roller would be quickly gelled, causing an accumulation of matter which would ruin the adhesive supply and contaminate the surface of the corrugating roll. Conventionally, therefore, the adhesive applicator roller is moved away from the corrugating roll whenever the single facer stops consuming medium.
Since high precision is required in positioning the adhesive applicator roller, the mechanism for elevating and lowering the roller is both massive and complicated. The weight of the massive roller further compounds the problem.
Heretofore, the mechanism for raising and lowering the adhesive applicator roller was actuated through a complex arrangement of links and an air-oil circuit. This type circuit was necessary to provide the smooth operation required. One disadvantage of that mechanism was that no self-actuating emergency release of the pressure could be readily incorporated to lower the adhesive roller to its inoperative position in the event of an accidental wrap of corrugating medium around the corrugating roll. An accidental wrap occurs if the medium web is accidentally ruptured. If an accidental wrap occurred the machine was invariably damaged. Consequently, there has been a need for a system to provide positive support for the applicator roll and be self-releasing in the event of a wrap-up of material on the periphery of a corrugating roll.